And the show must go on 😉 Here are the results of my last two tests. On Saturday it started and ended cloudy, Sunday was a perfect night! Thats great, because I was able to adjust parameters right after the first sessions data analysis and test it immediately during the next night 🙂
In summary, I experienced again a “crash light”, after 5-6 sessions without problems. It really felt better and more stable with the new MGEN cables for a short time… What a shame!
On the other side, I could use again 100% of the sub exposures, apart from the exposure just before the crash happened.
Basically it’s the same setup like in Part IV. Differences are highlighted in orange.
- Dual 50mm Guide Scope 205mm f/4.1 with helical focusser
- Canon EF 400mm mounted with original Canon ring
- Canon EOS 70Da
- Lacerta MGEN II
- New set of MGEN cables
- Powered by 12V 22Ah Power Tank
- Payload weight: 5.25kg
- Counterweights: 7.35kg (before: 6kg)
The first evening I tested again with new settings. There are more counterweights to reduce inertia moment arm and I’ve loosened gear meshing slightly more.
MGEN tolerance I’ve increased to 0.25, based on a calculation I found in the net. I’ll post the source once I find it 😉
MGEN Analysis Results
Test 1 – Oct. 9, 2021
- Gear Meshing RA: -3/4 turn (before: -1/2)
- Gear Meshing DEC: -5/4 turn (before: -1/1)
- Guide Speed: RA 0.50x, DEC 0.25x
- MGEN RA: NUM 1, Tol. 0.25 (before: 0.20), Aggr. 50-70% (before: 70%), Mode 2
- MGEN DEC: NUM 1, Tol. 0.25 (before: 0.20), Aggr. 50-70% (before: 70%), Mode 2
The values are slightly better than before, but there are still the DEC ramps!
For 600 seconds the exposures looks OK to me.
Test 2 – Oct. 10, 2021
After the results from test 1 I decided to loosen a bit the DEC axle stiction and repeat the test with almost the same settings.
Axle stiction adjustment instructions by iOptron: https://www.ioptron.com/v/Support/CGEM2x_AxleStictionAdjustment.pdf
There were no significant differences between 50% and 70 MGEN aggressivity, so I choosed 60% aggressivity for RA and DEC.
- Axle Stiction Adjustment: -1/8 turn
- MGEN RA: Aggr. 60%
- MGEN DEC: Aggr. 60%
Guided exposure #3 starts very well, but at the end the same pattern as before axis stiction adjustment. So I’ll need to loosen it a little bit more.
Again I’m very pleased about the stars on 600 seconds sub exposures 🙂
Looking forward to the results after DEC axle stiction re-adjustment.
That’s how the 9. sub exposure looked like during my NGC 891 session, which I started right after the tests. Afterwards I had to reboot everthing (back to zero position, power off, power on and back to the object) because the GEM28 once again didn’t respond to MGEN signals anymore. I also restarted the MGEN. The remaining time everything went fine.